The primary purpose of ASM is to prevent the competition from using a
general purpose FS for their databases. Cluster-consistent file system
can get an open source DB like MySQL, PostgreSQL or Firebird one giant
step closer to something like RAC.
The problem with ASM is that it cannot be accessed by the general purpose
file tools like tar, cpio, cp, od or fuser. If your dump file is on ASM,
you can't use bzip2 to compress it. The only compression utility
available on ASM is "rm", from asmcmd. That achieves 100% compress ratio,
but decompression can be tricky. No mv, either, no moving archive logs to
a less crowded place. ASM is a non-standard form of storage and I would
stay away from it, wherever I can. Unfortunately, I can't stay away from
it with RAC.
That is the same thing that will eventually kill off Exadata: you have to
buy a rather expensive SAN device that you can only utilize for Oracle. I
can imagine the facial expression of my CIO when asking: "what do you
mean, that I cannot store files there?" Rolls Royce is a better car than
Toyota Camry, but there are other considerations, too. BTW, here are some
cool T-shirts: